Utah authorities say a courageous teenage student helped foil a bomb plot that could have injured hundreds at her public high school near Salt Lake City.

Roy High School sophomore Bailey Gerhardt, 16, shared a text message with a school administrator that led law enforcement to a pair of students with detailed plans to set off a bomb during an assembly.

"If I tell you one day not to go to school, make d--n sure you and ... are not there," the message read, according to court records.

Officials said 18-year-old Dallin Morgan and his 16-year-old friend's plot to bomb their Utah high school was planned months ahead.

Their goal? Do as much harm as possible to the 1,500 students at Roy High School, located about 30 miles north of Salt Lake City.

The 16-year-old suspect told investigators he was so "fascinated" by the idea of a massacre that he visited Colorado's Columbine High School in December and interviewed the principal about the shootings.

The two then studied their own school's security system and logged hundreds of hours on flight simulator software. Their plan was to escape after the attack by flying out of the country.

"This was not idle chatter and that was early on recognized that there was significant thought, there was significant purpose," Roy Chief of Police Gregory Whinham said.

"I'm terrified to be at school right now," Maranda Moyeswild, a junior, said. "I have a lot to live for - I don't want to die at school."

The suspects' parents are cooperating with authorities. Meanwhile, everyone is trying to understand just what went wrong.

"Who are these two young people that looked ordinary to everybody in their performance, their activities?" Whinham asked. "What was the thing that turned them into somebody that wanted to hurt other people?"

Both suspects are being held at Weber County jail on suspicion of conspiracy to commit mass destruction. Authorities haven't ruled out additional charges.